The present invention relates to a digital VCR for reproducing video data and audio data that are encoded and recorded on a magnetic tape.
U.S. Pat. No. 4,631,603 describes the recording of a signal (hereinafter referred to as a CP signal) in the vertical blanking interval of an analog TV signal. The copyright protection signal comprises a plurality of pairs of pulses, each pair in turn comprising a synchronizing pulse (such as a horizontal sync pulse) and a positive pulse. When an attempt is made to dub the contents of the tape, the CP signal disturbs the AGC of the recording VCR, thereby preventing the recording VCR from producing a faithful copy of the original tape. In this manner, the CP signal copyright protects the copyright to the contents of the original tape.
Unlike the analog VCR discussed above, there have been previously proposed digital VCRs that are not compatible with analog CP signals. These digital VCRs record compressed digital image data; signals that do not directly relate to the image (such as a vertical blanking interval or a horizontal interval) are not recorded onto the tape. Since the vertical blanking interval and the horizontal blanking interval are not recorded, the CP signal is also not recorded because the CP signal typically is included in the vertical blanking interval of the input video signal. The present invention is directed to a signal format and to a compatible reproducing apparatus that protect recorded video and audio data against dubbing by either a digital VCR or an analog VCR.